Origin of Species Variorum

→ the alimentary canal respires, digests, and excretes 1859 1860 1861 1866 1869

OMIT 1872

→ Cobites. 1859 1860 1861 1866 1869

Cobites the alimentary canal respires, digests, and excretes. 1872

→ a part or 1859 1860 1861

the whole or part of an 1866 1869 1872

→ wholly change its nature 1859 1860 1861

greatly change its nature 1866

OMIT 1869 1872

→ steps. 1859 1860 1861 1866

steps greatly change its nature. 1869 1872

↑ 1 blocks not present in 1859 1860 1866 1869 1872; present in 1861

Certain plants, as some Leguminosæ, Violaceæ, &c., bear two kinds of flowers; one having the normal structure of the order, the other kind being degraded, though sometimes more fertile than the perfect kind: if the plant ceased to bear its perfect flowers, and this did occur during several years with an imported specimen of Aspicarpa in France, a great and sudden transition would apparently be effected in the nature of the plant.

→ might with ease 1859 1860

might 1861

or means of performing the same function might 1866

for performing the same function might 1869

might readily 1872

→ fish, or, for I do not know which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder. 1859 1860 1861 1866

fish. 1869

fishes. 1872

passed, we should have to look to very ancient ancestral forms, long since become extinct.

We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; thus →the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish →Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might

~~easily~~

easily

specialise, if any advantage were thus gained, →a part or organ, which had

previously performed

performed

two functions, for one function alone, and thus →wholly change its nature by insensible →steps. ↑ Two distinct organs sometimes perform simultaneously the same function in the same individual; to give one instance, there are fish with gills or branchiæ that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ having a ductus pneumaticus for its supply, and being divided by highly vascular partitions. In

all such

these

cases

cases,

one of the two organs →might with ease be modified and perfected so as to perform all the

work,

work

~~by itself,~~

by itself,

being aided during the

progress

process

of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be

wholly

quite

obliterated.

The illustration of the swimbladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one

pur- pose,

purpose,

namely,

namely

flotation, may be converted into one for a

widely

wholly

different purpose,

namely,

namely

respiration. The

swim-bladder

swimbladder

has, also, been worked in as an accessory to the auditory organs of certain →fish, or, for I do not know which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder.